Crossing over and C.O.M.

[LiquidFeet]

[.... In other words, there is no “pull back” maneuver required that uses hamstring contraction that can get in the way of a loosely flexing stack from top to bottom. This is an example of lowering the kinesthesis to the foot and ankle, a constant tension that drives the ski directly through the boot. To me the key to good skiing is the “automation” of of movement patterns that require less muscular effort but also less focus and management of the details. It is “gravity” powered and drives the inside ski into service. That said, I believe that muscularly activated “pull back” dorsiflexion (inside or both skis) is an excellent correctional, developmental and tactical accessory motor pattern depending on the scenario.

Nice post. Interesting take on dorsiflexion and plantarflexion.
(I see what you did there at the end.)

 

[mdf]

Ok, this is what I was thinking of...
https://ojs.ub.uni-konstanz.de/cpa/article/view/3891/3609

Unfortunately he averages over the turn, so we can't see shifts. The labels on the bars correspond to regions under the foot in the picture.

So most under big toe, then ball, then inside side of heel.

 

[Uke]

Good stuff Doby Man. I agree with alot of the points you made above. I'm well aware that the current cat's pajamas is the idea of migrating from ball to arch/heel during turns. It's certainly a way of making turns that lots of really good skiers are using. I just don't subscribe to the notion of letting my CoM drift back relative to the BoS in every turn. It's less efficient. It's more tiring. It requires a bigger movement to come forward again at the start of each turn. It puts me on my heels for a larger proportion of time in each turn - not a great place to be to handle unexpected forces due to terrain or conditions. Do I employ that technique occasionally? Sure.
Do I want to do that intentionally from turn to turn to turn? Heck no.

This isn't something new or even newly fashionable, the concept has been around for the 45 years that I've been paying attention to ski technique. Have to ask Kneale B to find if it was around in the leather boots and wood ski days

If you find that is less efficient and tiring then you are doing it wrong. For me this concept makes everything easier and less fatiguing the arcs become effortless and sometimes seem to be on auto-pilot.

I have to make no movement to 'come forward' just release the old outside ski and presto-chango I'm feeling pressure on the tip of the new outside ski.

Pressuring the heel/tail of the ski is a great place to be as you come out of the apex of the arc and begin to prepare for transition. I might even go so far as to say it is exactly where you want to be.

Do I intentionally want to employ a concept that has been around through several changes of equipment and teaching methodologies and has been used by the top practitioners of our sport for all that time. Well, yea.

 

[Kneale Brownson]

Rocking horse (tip/waist/tail) has been around since at least the advent of plastic boots. That was prior to my joining PSIA in 1969.

Surely I'm not the only one here who skied in leather boots.

 

[François Pugh]

Where your CoM is and where the pressure is (fore-aft) doesn't have to be the same at the same time; it often isn't. Just say'n.

Warning Physics Ahead!

The ground-reaction force vector and position of the Centre of Mass (CoM) result in the CoMs acceleration; control the force and you control your acceleration, which affects changes to your velocity vector, which determines where you go (position). Where you go puts you in position to control the force. Think line of action of the force and position of base of support and CoM.

Applied force directly affects the CoM's acceleration, but only affects its position indirectly through acceleration and velocity. I am quite often forward and moving to the back and apply pressure through the tails to slow down my CoMs rearward motion, typically just before I release the CoM from the turn.

That being said, if you integrated the force under my foot over time (averaged it out over time) you would likely (probably?) get some sort of normal probability distribution with a mean smack in the middle between ball of foot, little toe ball, and heel.

To me skiing as about moving, not about static positions re forward or backseat. You move through positions. Being forward gives you leverage to pressure the tips, but there's more to it than that. How fast you're moving fore or aft and more importantly how fast that speed is changing is what matters in the moment. It only matters transitorally, but integrated over time, transitory moments infinitely matter.

 

[Skisailor]

Rocking horse (tip/waist/tail) has been around since at least the advent of plastic boots. That was prior to my joining PSIA in 1969.

Surely I'm not the only one here who skied in leather boots.

Ha! Hi Kneale. Yup! That would be me - leather lace up boots, cable bindings, wooden skis.

And yes - I did not mean to imply that hobby horsing (as we call it) has not been around for a long time. I just stated my experience and observation that it is currently popular - at least in my ski school.

 

[Skisailor]

This isn'to something new or even newly fashionable, the concept has been around for the 45 years that I've been paying attention to ski technique. Have to ask Kneale B to find if it was around in the leather boots and wood ski days

If you find that is less efficient and tiring then you are doing it wrong. For me this concept makes everything easier and less fatiguing the arcs become effortless and sometimes seem to be on auto-pilot.

I have to make no movement to 'come forward' just release the old outside ski and presto-chango I'm feeling pressure on the tip of the new outside ski.

Pressuring the heel/tail of the ski is a great place to be as you come out of the apex of the arc and begin to prepare for transition. I might even go so far as to say it is exactly where you want to be.

Do I intentionally want to employ a concept that has been around through several changes of equipment and teaching methodologies and has been used by the top practitioners of our sport for all that time. Well, yea.

Sorry Uke. I'm just stating my observations and my experience - in my own skiing and in my observation of colleagues when we ski together. It's a relative statement. Compared to my preferred technique, moving back to the heel in every turn is far less efficient - especially in any condition other than smooth groomed snow, where I strive to minimize the amount of time spent away from balancing over the part of the foot that Ron Kipp describes as the place where we are anatomically and biomechanically the most agile. .

Perhaps skiers who are younger, stronger, or more fit can deal with the issues that can arise from letting our weight drift back to the heel in every turn, but I choose not to ski that way. And my observation - even relative to our clinicians at times - is that when we arrive at the bottom of a long continuous off piste run, they are breathing hard and I am not..

I tend to place a higher priority on efficiency than many skiers. It's not right or wrong - just a preference. But I DO believe that in general, as instructors of recreational skiers - not race coaches, we do not focus enough on movement patterns that will give that gift of efficiency to our students.

 

[JESinstr]

Guess we'll just have to agree to disagree. I posted this recently in a PSIA forum thread after seeing video that was posted here in another of the recent ski school threads. In it, US Ski Team Coach Ron Kipp describes the ball of the foot as "the anatomical and biomechanical optimal place where we are the most agile". I totally agree. Balancing there maximizes our options in any given moment. And in every direction.

Sorry Uke. I'm just stating my observations and my experience - in my own skiing and in my observation of colleagues when we ski together. It's a relative statement. Compared to my preferred technique, moving back to the heel in every turn is far less efficient - especially in any condition other than smooth groomed snow, where I strive to minimize the amount of time spent away from balancing over the part of the foot that Ron Kipp describes as the place where we are anatomically and biomechanically the most agile. .

Perhaps skiers who are younger, stronger, or more fit can deal with the issues that can arise from letting our weight drift back to the heel in every turn, but I choose not to ski that way. And my observation - even relative to our clinicians at times - is that when we arrive at the bottom of a long continuous off piste run, they are breathing hard and I am not..

I tend to place a higher priority on efficiency than many skiers. It's not right or wrong - just a preference. But I DO believe that in general, as instructors of recreational skiers - not race coaches, we do not focus enough on movement patterns that will give that gift of efficiency to our students.

Funny, In Ron Kipp's video that you reference (BTW that is a great and very enlightening video) I don't hear him saying anything about balancing over the " place where we are anatomically and biomechanically the most agile". This tells me you made an assumption that is not supported by all that follows in Ron's video.

To be successful in skiing we must first understand that we are dealing with 2 very different and commanding forces. One that is always present called Gravity and one that comes (generated) and goes called Centripetal .

Priority 1 is to remain upright and that requires balancing our weight (a gravitational term) against the pull of gravity. Priority 2 is to manage the centripetal force generated and that requires balancing our mass (COM) against the ski

As velocity increases into a turn, these two priorities diverge. So we need to differentiate between balance to remain upright and balance (pressure management) with the ski. The magic of the boot is that it allows you to pressure the center of the ski (area under the ball of the foot ) through flexion while remaining in control of upright balance through the arch using the supporting "footers" that are the large ball of the foot and the heel. IMO, key to making this happen is to have proper control and management of the "flex complex" (ankles,knees and hips). This is where Ron is going when he talks about creating tension.

To suggest that there is one pace of balance and pressure while skiing redefines meaning of the word dynamic.

 

[Kneale Brownson]

At 78, I couldn't ski top to bottom like I do without being efficient.

 

[Skisailor]

Funny, In Ron Kipp's video that you reference (BTW that is a great and very enlightening video) I don't hear him saying anything about balancing over the " place where we are anatomically and biomechanically the most agile". This tells me you made an assumption that is not supported by all that follows in Ron's video.

To be successful in skiing we must first understand that we are dealing with 2 very different and commanding forces. One that is always present called Gravity and one that comes (generated) and goes called Centripetal .

Priority 1 is to remain upright and that requires balancing our weight (a gravitational term) against the pull of gravity. Priority 2 is to manage the centripetal force generated and that requires balancing our mass (COM) against the ski

As velocity increases into a turn, these two priorities diverge. So we need to differentiate between balance to remain upright and balance (pressure management) with the ski. The magic of the boot is that it allows you to pressure the center of the ski (area under the ball of the foot ) through flexion while remaining in control of upright balance through the arch using the supporting "footers" that are the large ball of the foot and the heel. IMO, key to making this happen is to have proper control and management of the "flex complex" (ankles,knees and hips). This is where Ron is going when he talks about creating tension.

To suggest that there is one pace of balance and pressure while skiing redefines meaning of the word dynamic.

Just to be clear - I haven't made any assumptions, nor have I based any of my technique on Ron Kipp's video. My mentor is Ursula Howland from Big Sky and I am a proponent of her technique. But Ron's statement about the undeniable anatomical fact regarding the ball of the foot definitely supports that one particular aspect of Ursula's approach. There is alot more to her extremely efficient and dynamic technique than just centering our weight over the ball of the foot.

I actually agree with alot of what you say above. But I do disagree that refining one's balance point to a smaller part of the foot is somehow less dynamic. On the contrary - it requires that "proper control and management of the flex complex" as you state - flexing and extending ankle, knee and hip in order to keep the weight centered in that
"biomechanically most agile" location. Ursula likes to describe it as learning to balance on a unicycle vs. a bicycle. Except to improve upon her analogy, you have to imagine that there is something extra special about the unicycle tire and the front tire of the bicycle.

Also in the interest of clarity (and in answer to some of the other posts in this thread) - there is some language stuff here that might be confusing. Since the balance point of most skis is under the place where the ball of our foot sits (park skis are a notable exception), when I center my weight there, I DO consider myself to be centered on the ski. From that place I can apply equal pressure from tip to tail. I just like to use the word "forward" with students for reasons that I explained earlier.

 

[JESinstr]

Just to be clear - I haven't made any assumptions, nor have I based any of my technique on Ron Kipp's video. My mentor is Ursula Howland from Big Sky and I am a proponent of her technique. But Ron's statement about the undeniable anatomical fact regarding the ball of the foot definitely supports that one particular aspect of Ursula's approach. There is alot more to her extremely efficient and dynamic technique than just centering our weight over the ball of the foot.

I actually agree with alot of what you say above. But I do disagree that refining one's balance point to a smaller part of the foot is somehow less dynamic. On the contrary - it requires that "proper control and management of the flex complex" as you state - flexing and extending ankle, knee and hip in order to keep the weight centered in that
"biomechanically most agile" location. Ursula likes to describe it as learning to balance on a unicycle vs. a bicycle. Except to improve upon her analogy, you have to imagine that there is something extra special about the unicycle tire and the front tire of the bicycle.

Also in the interest of clarity (and in answer to some of the other posts in this thread) - there is some language stuff here that might be confusing. Since the balance point of most skis is under the place where the ball of our foot sits (park skis are a notable exception), when I center my weight there, I DO consider myself to be centered on the ski. From that place I can apply equal pressure from tip to tail. I just like to use the word "forward" with students for reasons that I explained earlier.

I just don't get it. If you center your weight (again a term specific to gravity) over the center of the ski, you can ONLY apply equal pressure and that is only while gravity remains as the dominant force for pressure! Since the waist of the ski is to the rear of center what does that say about turn shape? If you are talking about a "Balance Home", I can understand why you might consider the ball of the foot but I still disagree. IMO, "Balance Home" is the controllable compressing of the arch (flexing) between the ball of the foot and heel which serves the ability to balance against both gravitational and centripetal forces.

I think the unicycle to bicycle analogy is deeply flawed. While it might be appealing at first glance, show me someone rounding a curve at 20 mph on a unicycle vs someone on a bike and tell me who has the most control of forces coming to bear and a better chance of making it through the curve.

Relating the above to a ski turn. You are on a moving platform (ski) that requires dynamic pressure management to successfully bend and shape that ski so as to form a circular path. You say that having a single stable point of balance for managing the capability of bending and shaping is better than a range of balance platform supported by two stable points? If that is your position I only ask why aren't the center of the ski and the center of shape in the same place?

Regarding efficiency. Efficiency has little to do with where you stand but everything to do with how you get there.

Finally, I do appreciate your attempt to clarify confusion but that's what happens when you use simple terms like "forward" to address complex situations.

 

[mdf]

center your weight (again a term specific to gravity)

I am sure nearly everyone who is speaking loosely and means "effective weight" (or whatever phrase you want to coin), which definitely includes centrifugal forces as well. It is whatever your body feels as weight in the moment.
(Or "that virtual force which is opposed by centripetal force" if centrifugal is a hot button term.)

 

[Skisailor]

It is a balance home (I like that phrase) and it certainly is not just with respect to gravity but with regard to all of the forces at play in skiing and our ability to stay upright and not fall over during a dynamic turn. As already described, I use the whole foot for balancing (the whole foot is in contact with the boot sole) but the weight is still centered over the ball of the foot. If you are feeling your weight equally distributed between the ball and heel to provide yourself with a wider platform, then your weight is actually centered for some greater proportion of the time over your arch - not the best place from which to make subtle, nuanced balancing movements or to react to the dynamic and ever changing forces at play while skiing - particularly once we get off the groomed slopes. Skiing is NOT just about bending and shaping the skis. It is also about being able to manage our bodies, more specifically our CoM, in a way that keeps us from falling over. And human beings cannot do that part of the task as effectively from our arches or heels as we can from the ball of the foot.

I do disagree with your statement about efficiency. It has ALOT to do with where we balance (the more time we spend on our arches or heels, the more time we will likely spend engaging our large muscle groups to stay in balance) and ALSO alot to do with how we manage the CoM to BoS relationship during turns.

I find zero impact on my ability to shape precise turns using this technique. And with regard to the use of the word forward, maybe it doesn't work very well on a ski forum, but it is quite effective for the concepts I want to focus on with my students.

Come to Big Sky and take a lesson with Ursula and then maybe you will "get it". I mean that humbly and sincerely. She is a better messenger for her technique than I am. A few years back she received NRM's Black Diamond award and the nomination letter from another ski school director closed with the line: "Everyone who skis with her is moved and changed by the experience."

 

[Skisailor]

I am sure nearly everyone who is speaking loosely and means "effective weight" (or whatever phrase you want to coin), which definitely includes centrifugal forces as well. It is whatever your body feels as weight in the moment.
(Or "that virtual force which is opposed by centripetal force" if centrifugal is a hot button term.)

Posted before I saw this. Yes. Thanks. I am not a physics professor. By all means use effective weight or whatever works for you. My goal is not to persuade anyone but to at least understand and be understood.

 

[JESinstr]

I am sure nearly everyone who is speaking loosely and means "effective weight" (or whatever phrase you want to coin), which definitely includes centrifugal forces as well. It is whatever your body feels as weight in the moment.
(Or "that virtual force which is opposed by centripetal force" if centrifugal is a hot button term.)

I understand the point you are trying to make mdf.
Unfortunately if you "loosley" ask 100 people to put their weight over the balls of their feet most will lead with their upper mass. This is how we humans accomplish that goal when relating to gravity and having a solid surface to create friction . Take away friction and leading with upper mass becomes problematic.

 

[mdf]

I understand the point you are trying to make mdf.
Unfortunately if you "loosley" ask 100 people to put their weight over the balls of their feet most will lead with their upper mass. This is how we humans accomplish that goal when relating to gravity and having a solid surface to create friction . Take away friction and leading with upper mass becomes problematic.

Ok, you probably have a valid point if you come at it from "how does an average student interpret that" direction.

 

[Uke]

It is a balance home (I like that phrase) and it certainly is not just with respect to gravity but with regard to all of the forces at play in skiing and our ability to stay upright and not fall over during a dynamic turn. As already described, I use the whole foot for balancing (the whole foot is in contact with the boot sole) but the weight is still centered over the ball of the foot. If you are feeling your weight equally distributed between the ball and heel to provide yourself with a wider platform, then your weight is actually centered for some greater proportion of the time over your arch - not the best place from which to make subtle, nuanced balancing movements or to react to the dynamic and ever changing forces at play while skiing - particularly once we get off the groomed slopes. Skiing is NOT just about bending and shaping the skis. It is also about being able to manage our bodies, more specifically our CoM, in a way that keeps us from falling over. And human beings cannot do that part of the task as effectively from our arches or heels as we can from the ball of the foot.

I do disagree with your statement about efficiency. It has ALOT to do with where we balance (the more time we spend on our arches or heels, the more time we will likely spend engaging our large muscle groups to stay in balance) and ALSO alot to do with how we manage the CoM to BoS relationship during turns.

I find zero impact on my ability to shape precise turns using this technique. And with regard to the use of the word forward, maybe it doesn't work very well on a ski forum, but it is quite effective for the concepts I want to focus on with my students.

Come to Big Sky and take a lesson with Ursula and then maybe you will "get it". I mean that humbly and sincerely. She is a better messenger for her technique than I am. A few years back she received NRM's Black Diamond award and the nomination letter from another ski school director closed with the line: "Everyone who skis with her is moved and changed by the experience."

You keep making statements as fact that are not facts but rather opinion. You insist that we balance better on the balls than on the whole foot. The structure of the foot and the lower body argue against that conclusion. If you want to test it just stand on both feet, fairly easy for most of us, could do it all day and never have to make and balance corrections or the ones I am making are so subtle that I don't notice them. Now shift the pressure under foot forward. If you are like me or the many people I have done this with the further forward the pressure the more and larger the corrective balancing movements you make become and this is just standing there on a flat floor. Personally, I want to start from the most stable stance if I have to deal with a constantly changing surface.

'over your arch - not the best place from which to make subtle, nuanced balancing movements or to react to the dynamic and ever changing forces at play while skiing'. What prompts this statement I see no reason why i can't make the movements you mention just as well from the center of the arch. Again the structure of our bodies and the dynamics of skiing argue in favor of the centered stance being more efficient.

Don't think I have to 'get it'. After 30+ years and thousands of students who have been moved and changed by the experience (or so they tell me), I think I got it a long time ago and have spent my time passing it along.

uke

uke.

 

[Lauren]

It must be summer...I stumbled into a ski technique thread AND read the whole thing...furthermore, I'm going to comment

'over your arch - not the best place from which to make subtle, nuanced balancing movements or to react to the dynamic and ever changing forces at play while skiing'. What prompts this statement I see no reason why i can't make the movements you mention just as well from the center of the arch. Again the structure of our bodies and the dynamics of skiing argue in favor of the centered stance being more efficient.

I'd tend to agree with this. The most stable shape is a triangle, which is one reason I'd agree that you should be over your arch for the most stable balance point....the ball of your foot (big toe ball), the ball on the little toe, and your heel creates a triangle, giving you a stable platform to balance on.

IMO, there is a reason every single manufacturer puts the mark on your boot in the center (this mark generally lands on your arch just behind the ball of your foot). The manufacturer then marks a ski with the location that it is designed to be skied at (generally the center of the side cut). And there's a reason when you match these lines up it skis "correctly" for a majority of the skiing population. Now, everyone is created anatomically different, so it's really a "one size fits most" rather than "all"...which would explain why some people like certain skis mounted forward or back of "center mark".

 

[Skisailor]

You keep making statements as fact that are not facts but rather opinion. You insist that we balance better on the balls than on the whole foot. The structure of the foot and the lower body argue against that conclusion. If you want to test it just stand on both feet, fairly easy for most of us, could do it all day and never have to make and balance corrections or the ones I am making are so subtle that I don't notice them. Now shift the pressure under foot forward. If you are like me or the many people I have done this with the further forward the pressure the more and larger the corrective balancing movements you make become and this is just standing there on a flat floor. Personally, I want to start from the most stable stance if I have to deal with a constantly changing surface.

'over your arch - not the best place from which to make subtle, nuanced balancing movements or to react to the dynamic and ever changing forces at play while skiing'. What prompts this statement I see no reason why i can't make the movements you mention just as well from the center of the arch. Again the structure of our bodies and the dynamics of skiing argue in favor of the centered stance being more efficient.

Don't think I have to 'get it'. After 30+ years and thousands of students who have been moved and changed by the experience (or so they tell me), I think I got it a long time ago and have spent my time passing it along.

uke

uke.

I think the only thing that I have stated as fact and which I continue to stand behind, is the idea that physiologically the ball of the foot offers the human body opportunities to move in ways that we cannot when we are balanced over the arch or heel. I don't think that I am alone in this assessment of human anatomy, and that is why I posted that quote from Ron Kipp.

I think if you read back through my posts, you will see that I have gone out of my way in other matters to state that this way of skiing is a preference of mine - and a style - and I tried to explain why I prefer it in the interest of sharing ideas. I've made it clear that it is not right or wrong to ski another way. I also do not think that I have stated my opinions any more strongly than other posters including you - who told me definitively that if I wasn't felling what you feel than I must be "doing it wrong". I've said nothing of the sort in my own posts. I will use more IMHOs in future if you like - though I don't notice other posters feeling the need to do so in relating their own ideas.

I think it's really great that you've had such success in your teaching career. And I'm very sincere about that. Truly. It's awesome. I'm glad that you've "got it right" and that you are speaking the courage of your convictions.

Since my posts seem to be upsetting to you for some reason, please feel free to ignore them in future.

 

[Skisailor]

Hi @lelemmac !!!! Good to see you here! Are you coming back to Big Sky for the Gathering?? Would be great to make turns together.

I totally agree that the big toe and little toe "balls" and heel create an awesome stable triangle. But if we get farther into the weeds on it, what I am saying is that within that triangle our weight must be centered somewhere - some theoretical point through which the CoM is directed - that is not as big as that whole part of the foot you're describing.

So if we back that out into the real world - LOL - if you are truly feeling an equal amount of your weight on all 3 of those parts of your foot when you ski, in those moments, your weight is actually balanced somewhere in the middle of that triangle - somewhere under the arch. Would you agree? And the only point I'm making is that if we balance more behind the ball of the foot, we are not in quite as good of a "ready position" so to speak, to react to terrain and conditions, because anatomically, the ball of the foot can articulate and operate in ways that the arch of our foot cannot.

When I ski, I also feel all of those 3 parts of my foot just as you're describing. So the platform is there - at the ready if I need it. But my weight is directed, centered more, through the ball of my foot than the arch. It's a pretty subtle difference! But as I've gotten better at it (i.e. able to focus my balance there more of the time) by working with Ursula - I've noticed a huge positive difference in my skiing.